The invention is directed to a suspension system for a vehicle seat.
Any vehicle seat requires some apparatus to absorb shocks transmitted through the vehicle wheels and suspension system to the passenger compartment. Large vehicles such as tractor-trailers and agricultural vehicles employ elaborate seat suspension systems for the driver and passenger seats to absorb shocks and damp vibration of the seat near its natural frequency. The absorption and dampling features minimize the discomfort to the operator of the vehicle and its passengers; thus the driver can operate a vehicle for a longer period of time in greater comfort and without tiring. Because of the space available in the passenger compartments of large vehicles, and because of the relatively high cost of such vehicles, the seat suspension systems are frequently complex, bulky and expensive. See, for example, Radke et al., U.S. Pat. No. 3,325,136. The parallelogram mechanism depicted there requires substantial vertical space, rendering the device less useful in smaller vehicles.
Lower cost vehicles, such as vans, pickup trucks, motor homes and fourwheel-drive vehicles have traditionally employed seat suspensions incorporating only lightweight springs to minimize cost and complexity, and because of the limited space available in such vehicles. Because these vehicles may also be used off of roads, their suspension systems are quite stiff. This insures that the suspension will not bottom out when the vehicle is driven on a rough surface. However, still suspension systems are inherently disadvantageous when an offroad vehicle is driven on a highway, because they readily transmit vibrations to the driver and passengers. This problem is aggravated by the limited space available for a seat suspension system in these vehicles. Furthermore, given the relatively lower cost of these vehicles and the limited space available in their passenger compartments, it is desirable that vehicle suspensions for these applications be economical and also capable of accomplishing their functions in a smaller space than was previously possible.